Nitrogen Budget for Tomatoes and Peppers

Nitrogen is the one nutrient soil tests can't help with — it moves too fast. A written N budget, split through the season, is what separates 150 bu/acre tomato yields from 400+ bu/acre.

Total-N target

• Tomato (staked, plasticulture): 160–200 lb N/acre.
• Pepper (plasticulture): 140–180 lb N/acre.
• Tomato/pepper (bare ground): 100–140 lb N/acre.

Cover crop credits

• Crimson clover terminated at full bloom: −60 to −100 lb N.
• Austrian winter pea: −50 to −90 lb N.
• Hairy vetch: −80 to −120 lb N.
• Cereal rye alone: 0 credit (may temporarily tie up N).

Split schedule (plasticulture tomato, 180 lb target, no cover credit)

• Pre-plant (bed): 40 lb (22%) as 10-10-10 or comparable.
• Weeks 1–4 (fertigation, weekly): 10 lb/wk → 40 lb (22%).
• Weeks 5–10 (first fruit set through peak): 12 lb/wk → 72 lb (40%).
• Weeks 11–end: 7 lb/wk tapering → 28 lb (16%).

Petiole sap monitoring

Sap-nitrate testing every 10 days from first flower catches under- and over-N in real time. Target ranges (ppm NO₃-N in petiole sap):

• First flower: 1,000–1,200 ppm.
• First fruit set: 1,000–1,100 ppm.
• Peak harvest: 400–600 ppm.

Below range: increase weekly injection by 20%. Above range: cut in half — excess N delays ripening and thickens skins.